Apparatus for molding plastic material



Oct. 1, 1946. L. B. GREEN 4 APPARATUS FOR MOLDING PLASTIC MATERIAL FiledOqt. 21, 1943 l I l INVENTOR.

& I 1' Phi- BY 155.5. Gees/v La z! mfiw zqawm Patented Oct. 1, 1946UNITED APPARATUS FOR MOLDING PLASTIC MATERIAL Lee B. Green, Lakewood,Ohio Application October 21, 1943, Serial No. 507,119

1 Claim. 1

articles for the removal of fiash or gate material therefrom.

Another object of my invention is to provide a novel molding apparatuswhich is especially applicable to thermosetting materials and with whichpredetermined quantities of thermosetting material can be subjected tomolding pressure between cooperating plungers in a manner such thatarticles of superior quality can be rapidly produced without wastage ofmaterial or need for a trimming operation.

a A further object of my invention is to provide a novel moldingapparatus in which a pair of cooperating plungers carry a pill or thelike of moldable material into a mold body and subject the same tomolding pressure therein after which the plungers carry the moldedarticle out of the mold body.

Other objects and advantages of the invention will be apparent from thefollowing description when taken in conjunction with the accompanyingsheet of drawings, in which:

Fig. 1 is a partial longitudinal sectional view illustrating the novelmolding apparatus with the opposed plungers thereof in a position toreceive a pill of moldable material therebetween.

Fig. 2 is a similar view showing the pill carried into the mold body andabout to be subjected to molding pressure.

Fig. 3 is a similar view showing the pill being molded to article form.

Fig. 4 is another such longitudinal sectional view showing the moldedarticle shifted to the cooled section of the mold body, and

Fig. 5 is still another longitudinal sectional view showing the step ofdischarging the molded article.

As already indicated in a general way, my novel apparatus is especiallyvaluable for carrying out a molding operation where a proper quantity ofthe moldable material is in a preformed condition or shape commonlyreferred to as a pill. In the accompanying drawing to which moredetailed reference will now be made, I show such a pill l0 and also showa cap II as representing an article produced by my novel apparatus. Thepill l0 may be any one of various known materials which are capable ofbeing molded under 2. the application of heat and pressure. For example,it can be a thermoplastic material such as Tenite or it can be athermosetting material such as Bakelite.

The cap ll representing the molded article comprises a hollow bodyhaving transverse top or end wall [2 and an annular depending skirt l3provided with an internal screw thread It. The skirt [3 is ofcylindrical shape although my method is applicable to the production ofarticles of various other shapes.

In the drawing I show my novel apparatus as including a mold body l5 anda pair of opposed plungers l6 and I! which are slidably operable in anopening l8 of the mold body. The opening 18 can be conveniently referredtoas abore or cylinder and corresponds in cross-sectional shape with thearticle to be molded which, in this instance, is the cap II. Theplungers i6 and I! .also correspond in cross-sectional shape with thearticle to be molded and their adjacent ends cooperate to form a moldcavity 29 in a portion of the bore I8.

The inner end of the plunger H has a threaded projection Zla thereonwhich extends into the cavity 20 as a core for forming the internallythreaded recess in the cap H. The inner end of the plunger [6 islikewise shaped to correspond with the transverse top or end wall I2.ofthe cap. The mold body [5 comprises a plurality of connected sections2!, 22 and 23 having smooth- 1y aligned openings which form the bore I8.The section 2| supports the sections 22 and 23 and forms a guide for theplunger 11. The intermediate section 22 is a heated section having acoil 24 through which a suitable heating medium may be circulated. Thesection 23 is a cooled section having an opening or passage 25 thereinto which a suitable cooling medium may be supplied. Air spaces 26partially insulate the heated section 22 from the adjacent sections 2|and 23.

In Fig. 1 I show the plungers l6 and I! in a position to receivetherebetween the pill ll] of moldable material. In this pill-receivingposition the plunger IT has been entirely withdrawn from the mold bodyl5 and the plunger I6 has been extended so as to project through themold body. In this position the adjacent ends of the plungers l6 and I!are spaced apart so that the pill H] can be inserted therebetween andplaced on the end of the plunger l6.

Fig. 2 shows the plungers l6 and I! as havi been moved to a position inwhich their adjacent ends are located in the heated intermediate section22 and define the mold cavity 20 therein.

3 The pill l has been carried into the heated section 22 by the movementof the plungers to this position and the pill is about to be subjectedto molding pressure by the plungers.

In Fig. 3 the pill is shown as having been converted into the moldedarticle II as the result of molding pressure applied to the pill by theplungers I5 and I1 and the heating of the pill by the mold section 22.The pill contains the correct amount of material to fill the cavity 20and form the cap I I.

out of the heated zone and into the cooled zone in which the moldedmaterial is further solidified and hardened.

Further conjoint movement of the plungers l6 and I1 cause the article IIto be shifted out of the cooled mold section 23 to an articledischarging station 21 located outwardly of the mold section 23. At thisstation the plunger I! is moved away from the plunger I6 and, because ofthe interengagement between the threads of the projection H11 and theskirt 13, the article I moves with the plunger l1 and is thus separatedfrom the plunger IS. The molded article H can then be removed from theplunger 11 by being manually unscrewed from theprojection Zia, orpreferably, can be unscrewed by the engagement of a rubber-rimmed rolleror disk 28 therewith. Upon removal of the article II from the projection2| it drops out from between the plungers and falls into a suitablecontainer.

The plungers l6 and I! can be actuated in any suitable manner to producethe above described sequence of operations or steps. For example, theplunger 16 can be actuated by a suitable cam 29 engaging the lower endof the plunger and having an appropriate contour for raising andlowering the plunger and applying the desired pressure thereto. Thelower end of the plunger Hi can be held in seating engagement with thecam 29 by gravity or spring pressure. The plunger I! can be actuated bymeans of a suitable piston connected therewith and operable in the fluidcylinder 30 in response to either fluid or spring pressure or acombination of such pressures.

In the above described actuation of the plungers I6 and I! it should beunderstood that the movement of the plungers may be a substantiallycontinuous movement or, if desired, it can be an intermittent movementin which a desired interval of time is allowed for each step oroperation. It will be understood also, that the cam 29 can be driven byany suitable power means and that the operation of the cam and cylinder30 can be controlled by any suitable mechanism which will produce theabove described sequence of operations for the cooperating plungers.

From the foregoing descriptions and the accompanying drawing it will nowbe readily understood that I have provided a novel molding apparatus bywhich desired articles can be rapidly produced from predetermined bodiesor quantities of moldable material and which is especially valuable forproducing articles from thermosetting materials. It will be seen alsothat my novel apparatus also provides for the rapid and economicalproduction of molded articles of superior quality which do not requirethe trimming operations heretofore necessary for the removal of flash orgate material. Likewise it will be apparent that my novel apparatuspermits the use of any desired degree of pressure during the moldingoperation.

While I have illustrated and described my novel apparatus inconsiderable detail it will be understood, of course, that I do not wishto be correspondingly limited but regard my invention as including allchanges and modifications coming within the spirit of the invention andscope of the appended claim.

Having thus described my invention, I claim:

Molding apparatus for producing articles from thermosetting material orthe like comprising, a stationary mold body having heated and cooledsections and a bore extending through said sections, a pair of opposedplungers slidable in said bore and their adjacent ends having dieelements thereon corresponding in shape with the article to be molded,said adjacent ends being spaced apart and adapted to cooperate directlywith each other and with the wall of said bore so as to define a moldcavity for said article in said heated section, said plungerscooperating with said bore for rapidly producing individual moldedarticles from said material and being relatively movable so as to opensaid cavity for the reception of a pill or the like of the moldablematerial and to subsequently close the cavity and subject said materialto molding pressure therein in said heated section and said plungersbeing then movable conjointly in the same direction in said bore forshifting the mold cavity with the molded article therein out of saidheated section and through

